An embodiment relates to differential GPS reference stations. Global Positioning System (GPS) or other Global Navigation Satellite System (GNSS) receivers operate by tracking line of sight signals. These receivers typically require at least four or more satellites to be continuously available in an unobstructed line of sight of a satellite receiver on a vehicle. This is due to inherent delay in the signals generated by the satellites as the result of timing signals having some error or delay depending on what interferences the satellite signals may experience before being received by a GPS receiver. Therefore, for a moving vehicle, an absolute global position without errors may be difficult to achieve based solely on signals obtained by the satellites. It is well known that GPS errors may be as great as 30 meters.